The calls that you are receiving are certainly scam. Appears to be the work of extortion gangs. The arrest threat is a mere scare tactic, to coerce victims to cough up cash.

A debt collector could sue someone who has defaulted on payments for breach of contract and civil fraud, but they cannot have him /her arrested. They can only ask a court for damages. The use of word "arrest" in their conversation, gives away the con game, that these extortionists are playing out

Report the call to the Sheriff’s Office and also inform the caller (if he calls again) that the call is being taped as advised by the Police and he will be caught.

Another important trademark of scam is that the callers would not identify themselves, their office and it's physical address. (They might give fake details which you can easily determine as bogus if you check online)

You should ask them to send a Debt Validation Notice to you by mail (Don't give your address. They are supposed to have it) within 5 days of the phone call. Tell them that you are aware of legal provisions and will only respond to Debt Validation Notice sent in accordance with FDCPA. Period!